The Cisco Certified Network Associate (CCNA) exam consists of 50-plus questions with an allowed completion time of 90 minutes. There are the usual multiple-choice and drag-and-drop questions. However, there will be two to four simulation exercises that require hands-on interaction with one or more routers and switches.
It is important for a test-taker to know in advance what the topic areas are for these simulations. Here’s the scoop:
Familiarity with both Enhanced Interior Gateway Protocol (EIGRP) and Open Shortest Path First (OSPF) commands and troubleshooting techniques is required.
When doing OSPF network statements, it is important to know how to configure the wildcard mask. For example, the wildcard mask for 255.255.255.252 (/30) is 0.0.0.3.
With both EIGRP and OSPF, the purpose for the network statement in the routing protocol configuration is often misunderstood. It represents the interfaces on the router that will participate in OSPF or EIGRP. If a department in an enterprise is in network 192.168.90.0/24, for example, the interface on the router for this network should be included in a network statement, or the users in the department may not be able to communicate.
In the graphic, router Ajax must have a network statement for each of the four networks represented in order for the network to be included in the routing process. This is true for OSPF, EIGRP and RIPv2.
It is necessary to have an in-depth understanding of simple Network Address Translation (NAT) Overload, which is often called Port Address Translation (PAT). Knowledge of how to configure the inside local IP addresses with an Access Control List (ACL), the inside global addresses with a pool name, appropriate inside and outside interface configuration and a translation statement is needed.
There could be several troubleshooting scenarios, most of which have simple solutions:
- Wrong address and mask.
- Interface shut down.
- Routing parameters wrong.
To complete the simulations and the troubleshooting exercises, a very good understanding of IP address subnetting is required.
It is necessary to understand which IP address and mask are needed to support a specific number of hosts and what an appropriate default gateway address should be for those hosts.
IP Access Control Lists (ACLs)
This is an important topic and requires the ability to configure both standard and extended ACLs, both numbered and named. This includes the following:
- Source and destination IP address with wildcard mask.
- Source and destination TCP/UDP ports.
- Protocol field in IP header.
- Placement of ACL on interface in or out.
- The ability to deny a specific host from doing a function while allowing the rest of that host’s subnet to do the function.
In the graphic, the IP packets from the PC must go through the router to get to 10.10.10.10. You should explore and understand every possible combination of permit and deny scenarios on the router ACLs, along with the appropriate list direction on the interface.
In conclusion, the Cisco CCNA certification test is challenging. The best preparation is to attend the classes listed in the next section, utilize the cisco.com preparation tools and perhaps use other resources such as Cisco Press.
About The Author
Ray Dooley, BS, MBA, CCSI, CCNA, CCNP, CCDA, CCDP, SE, FE, has been a network professional in several capacities for over 30 years. He is the Global Knowledge course director for CCDA, ARCH, SWITCH, ROUTE, TSHOOT and ICMI. He has developed courses for Global Knowledge, Cisco and GE.